Re: [PATCH v5 14/16] cxl/pci: Add trace logging for CXL PCIe Port RAS errors

Bowman, Terry
2025-01-14T20:56:47Z

On 1/14/2025 5:49 AM, Jonathan Cameron wrote:
> On Tue, 7 Jan 2025 08:38:50 -0600
> Terry Bowman <terry.bowman@amd.com> wrote:
>
>> The CXL drivers use kernel trace functions for logging endpoint and
>> Restricted CXL host (RCH) Downstream Port RAS errors. Similar functionality
>> is required for CXL Root Ports, CXL Downstream Switch Ports, and CXL
>> Upstream Switch Ports.
>>
>> Introduce trace logging functions for both RAS correctable and
>> uncorrectable errors specific to CXL PCIe Ports. Additionally, update
>> the CXL Port Protocol Error handlers to invoke these new trace functions.
>>
>> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
>> Reviewed-by: Alejandro Lucero <alucerop@amd.com>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> An example print in commit message would help understand what the tracepoints
> look like.
>
> Few more things inline following on from earlier comments.
>
> Jonathan
>> ---
>> drivers/cxl/core/pci.c | 17 +++++++++++----
>> drivers/cxl/core/trace.h | 47 ++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 60 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
>> index 411834f7efe0..3e87fe54a1a2 100644
>> --- a/drivers/cxl/core/pci.c
>> +++ b/drivers/cxl/core/pci.c
>> @@ -663,10 +663,15 @@ static void __cxl_handle_cor_ras(struct device *dev,
>>
>> addr = ras_base + CXL_RAS_CORRECTABLE_STATUS_OFFSET;
>> status = readl(addr);
>> - if (status & CXL_RAS_CORRECTABLE_STATUS_MASK) {
>> - writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
>> + if (!(status & CXL_RAS_CORRECTABLE_STATUS_MASK))
>> + return;
>> +
>> + writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
>> +
>> + if (is_cxl_memdev(dev))
> As below. Drag to earlier patch.

Ok

>> trace_cxl_aer_correctable_error(to_cxl_memdev(dev), status);
>> - }
>> + else
> and perhaps check it's a port mostly for documentation purposes.
>

Ok

>> + trace_cxl_port_aer_correctable_error(dev, status);
>> }
>>
>> static void cxl_handle_endpoint_cor_ras(struct cxl_dev_state *cxlds)
>> @@ -724,7 +729,11 @@ static bool __cxl_handle_ras(struct device *dev, void __iomem *ras_base)
>> }
>>
>> header_log_copy(ras_base, hl);
>> - trace_cxl_aer_uncorrectable_error(to_cxl_memdev(dev), status, fe, hl);
>> + if (is_cxl_memdev(dev))
> As mentioned above, drag this if to the earlier patch.

Ok

>> + trace_cxl_aer_uncorrectable_error(to_cxl_memdev(dev), status, fe, hl);
>> + else
> For documentation purposes mostly I'd be tempted to have an is_cxl_port() check
> before calling the following.
>
>> + trace_cxl_port_aer_uncorrectable_error(dev, status, fe, hl);
>> +
>> writel(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK, addr);
>>
>> return true;
>> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
>> index 8389a94adb1a..681e415ac8f5 100644
>> --- a/drivers/cxl/core/trace.h
>> +++ b/drivers/cxl/core/trace.h
>> @@ -48,6 +48,34 @@
>> { CXL_RAS_UC_IDE_RX_ERR, "IDE Rx Error" } \
>> )
>>
>> +TRACE_EVENT(cxl_port_aer_uncorrectable_error,
>> + TP_PROTO(struct device *dev, u32 status, u32 fe, u32 *hl),
>> + TP_ARGS(dev, status, fe, hl),
>> + TP_STRUCT__entry(
>> + __string(devname, dev_name(dev))
>> + __string(host, dev_name(dev->parent))
> What is host in this case? Perhaps a comment.
host is a string initialized with value from dev_name(dev->parent). What
kind of comment would you like to see here?

Regards,
Terry

>> + __field(u32, status)
>> + __field(u32, first_error)
>> + __array(u32, header_log, CXL_HEADERLOG_SIZE_U32)
>> + ),
>> + TP_fast_assign(
>> + __assign_str(devname);
>> + __assign_str(host);
>> + __entry->status = status;
>> + __entry->first_error = fe;
>> + /*
>> + * Embed the 512B headerlog data for user app retrieval and
>> + * parsing, but no need to print this in the trace buffer.
>> + */
>> + memcpy(__entry->header_log, hl, CXL_HEADERLOG_SIZE);
>> + ),
>> + TP_printk("device=%s host=%s status: '%s' first_error: '%s'",
>> + __get_str(devname), __get_str(host),
>> + show_uc_errs(__entry->status),
>> + show_uc_errs(__entry->first_error)
>> + )
>> +);
>> +
>> TRACE_EVENT(cxl_aer_uncorrectable_error,
>> TP_PROTO(const struct cxl_memdev *cxlmd, u32 status, u32 fe, u32 *hl),
>> TP_ARGS(cxlmd, status, fe, hl),
>> @@ -96,6 +124,25 @@ TRACE_EVENT(cxl_aer_uncorrectable_error,
>> { CXL_RAS_CE_PHYS_LAYER_ERR, "Received Error From Physical Layer" } \
>> )
>>
>> +TRACE_EVENT(cxl_port_aer_correctable_error,
>> + TP_PROTO(struct device *dev, u32 status),
>> + TP_ARGS(dev, status),
>> + TP_STRUCT__entry(
>> + __string(devname, dev_name(dev))
>> + __string(host, dev_name(dev->parent))
>> + __field(u32, status)
>> + ),
>> + TP_fast_assign(
>> + __assign_str(devname);
>> + __assign_str(host);
>> + __entry->status = status;
>> + ),
>> + TP_printk("device=%s host=%s status='%s'",
>> + __get_str(devname), __get_str(host),
>> + show_ce_errs(__entry->status)
>> + )
>> +);
>> +
>> TRACE_EVENT(cxl_aer_correctable_error,
>> TP_PROTO(const struct cxl_memdev *cxlmd, u32 status),
>> TP_ARGS(cxlmd, status),